diff --git a/src/mpConfig.py b/src/mpConfig.py
index ec6900a..cd3135e 100644
--- a/src/mpConfig.py
+++ b/src/mpConfig.py
@@ -31,6 +31,11 @@ class MpConfig:
 	def getClientInterfaceCount(self):
 		raise Exception("To be implemented")
 
+	def interfaceBUPCommand(self, interfaceName):
+		s = "/home/mininet/git/iproute-mptcp/ip/ip link set dev " + interfaceName + " multipath backup "
+		print(s)
+		return s
+
 	def interfaceUpCommand(self, interfaceName, ip, subnet):
 		s = "ifconfig " + interfaceName + " " + ip + " netmask " + \
 			subnet
diff --git a/src/mpLinkCharacteristics.py b/src/mpLinkCharacteristics.py
index b4e81fa..bbb3801 100644
--- a/src/mpLinkCharacteristics.py
+++ b/src/mpLinkCharacteristics.py
@@ -6,12 +6,13 @@ class MpLinkCharacteristics:
 	tcNetemParent = "5:1"
 	tcNetemHandle = "10:"
 
-	def __init__(self, id, delay, queueSize, bandwidth):
+	def __init__(self, id, delay, queueSize, bandwidth, back_up=False):
 		self.id = id
 		self.delay = delay
 		self.queueSize = queueSize
 		self.bandwidth = bandwidth
 		self.netemAt = []
+		self.back_up = back_up
 
 	def addNetemAt(self, n):
 		if len(self.netemAt) == 0:
@@ -50,6 +51,7 @@ class MpLinkCharacteristics:
 		s =  s + "\tDelay : " + str(self.delay) + "\n"
 		s =  s + "\tQueue Size : " + str(self.queueSize) + "\n"
 		s =  s + "\tBandwidth : " + str(self.bandwidth) + "\n"
+		s =  s + "\tBack up : " + str(self.back_up) + "\n"
 		for l in self.netemAt:
 			s = s + "\t" + l.__str__() + "\n"
 		return s
diff --git a/src/mpMultiInterfaceConfig.py b/src/mpMultiInterfaceConfig.py
index 701462b..ff08277 100644
--- a/src/mpMultiInterfaceConfig.py
+++ b/src/mpMultiInterfaceConfig.py
@@ -38,16 +38,23 @@ class MpMultiInterfaceConfig(MpConfig):
 		self.router = self.topo.getHost(MpTopo.routerName)
 		i = 0
 		netmask = "255.255.255.0"
+		links = self.topo.getLinkCharacteristics()
 		for l in self.topo.switch:
 			cmd = self.interfaceUpCommand(
 					self.getClientInterface(i),
 					self.getClientIP(i), netmask)
 			self.topo.commandTo(self.client, cmd)
 
+			if(links[i].back_up):
+				cmd = self.interfaceBUPCommand(
+						self.getClientInterface(i))
+				self.topo.commandTo(self.client, cmd)
+
 			cmd = self.interfaceUpCommand(
 					self.getRouterInterfaceSwitch(i),
 					self.getRouterIPSwitch(i), netmask)
 			self.topo.commandTo(self.router, cmd)
+			print(str(links[i]))
 			i = i + 1
 
 		cmd = self.interfaceUpCommand(self.getRouterInterfaceServer(),
diff --git a/src/mpParamTopo.py b/src/mpParamTopo.py
index 9f96320..0d58e69 100644
--- a/src/mpParamTopo.py
+++ b/src/mpParamTopo.py
@@ -50,9 +50,12 @@ class MpParamTopo(MpParam):
 		for k in sorted(self.paramDic):
 			if k.startswith("path"):
 				tab = self.paramDic[k].split(",")
-				if len(tab) == 3:
+				bup = False
+				if len(tab) == 4:
+					bup = tab[3] == 'True'
+				if len(tab) == 3 or len(tab) == 4:
 					path = MpLinkCharacteristics(i,tab[0],
-							tab[1], tab[2])
+							tab[1], tab[2], bup)
 					self.linkCharacteristics.append(path)
 					i = i + 1
 				else: